Production of ammonium beryllium fluoride



Patented Nov. 28, 1950 PRODUCTION OF AMMONIUM BERYLLIUM FLUORIDE Henry C. Kawecki, Fleetwood, and Gordon F. Si n lOnS, Smith Temple, Pa, Z-SSigHOTs iii) The Beryllium Corporation, Reading, Pa., a corporation of Delaware No D'r'awing. Application August 18, 1948, Serial No. 44,997

9 Claims. 1 This invention relates to the recovery of beryllium from beryllium ores and, more particularly, to the recovery of the beryllium content of such ores in the form of ammonium beryllium fluoride from which beryllium inetal can readily be produeed.

The recovery of beryllium from its ores is complicated by the refractory nature of such ores as well as by the chemical similarity between beryllium and aluminum whieh is a common constitu ent or bfylliiiiil are. There have been numer- OuS suggestions afid trials of processes directed to the recovery or beryllium from its ores but most of these proposals have called for relatively e x-' pensive reagents which, in many instances, were required to react not only with the beryllium component of the ore but with other elements associated therewith.

The problem Of extraeting' beryllium from its ores without objectionable contamination by aluminum and other metals was solved successfully or the process deseribed and claimed by one Of Us; Kaweck'i, in Patent No. 2,312,297. This process comprises mixing the finely divided ore with sodium ferric fluoride and then roasting; or s'inteiihg the mixture. At the elevated roast ing or sintering temperature, the beryllium oxidecontent of the ore reacts with the sodium ferric fluoride to produce Sodium beryllium fiudfide which is water s'olubl'. The aluminum, silicon and iron oxides in the ore are not reacted upon by the sodium ferric fluoride with the result that the beryllium'content of the ore may be separated therefrom in reasohably pure condition. The s'odiiiih beryllium fluoride is extracted the sinter product by leaching, and the dissolved beryllium is precipitated as beryllium hydroxide by adding caustic soda to the solution. The beryllium hydroxide is then calcined to produce anhydrous beryllium oxide which is amenable to reduction to metallic beryllium.

Numerous methods have been described and used heretofore for reducing the beryllium of beryllium oxide to the metallic state. One of the more recent develop-merits in this field comprises the process des'erib'ed by Kje'llgren in the J our'nal of the Electrochemical Society, iioluifie 93, April 1948, pages 122 et seq. This pro'oedur comprises dissolving beryllium oxide of low aluminum content in a hot aqueous solution of ammonium .Iiuo

ride or hydrofluoric acid, or a mixture thereof. The mixture is heated,- say by steam, and is agi= tated for a substantialfier'io'd of time to efiect dissolution of the beryllium oxide. The resulting product comprises an aqueous solution or am 2 monium beryllium fluoride. This double fluoride can be recovered by crystallization, and its beryllium content may be recovered in metallic form by fusion with metallic magnesium as a recur: ing agent.

It is characteristic of the most successful commercial processes now in use that they involve the production or use of beryllium oxide. Recent investigations have indicated a possible health hazard in the presence of beryllium oxide; There is a definite health hazard in the use of such volatile corrosive substances as hydrofluoric acid. Accordingly, the cost of recovering beryllium by these prior art processes has been aggravated by the cost of safety precautions to guard against the escape into the atmsphere of injurious new ders' and fumes.

We have now devised a; method for the recovery of beryllium from its ores which is completely free of the health hazards noted hereihabove and which is characterized by simplicity and econo my. This method makes possible the production of ammonium beryllium fluoride, from which metallic beryllium may be readily produced, without the intermediate formation of beryllium oxide or other hazardous beryllium compounds and without the use of any reagents or condi tions which would present a health hazard.

The method of ioroducmg ammonium beryllium fluoride in accordance with our invention com prises heating beryllium ore with a double flue: ride of an alkali metal and iron or silicon to a temperature sufficiently high to effect decomposition of the ore with the resulting production of sodium beryllium fluoride, disintegrating the re-' sulting product in the presence 01'' added water, adding ammonium fiuosilicate to the disinte= grated product, and separating therefrom the resulting aqueous phase comprising a solution of ammonium beryllium fluoride. The ammonium beryllium fluoride can be recovered from its solution by any appropriate means such as crystal= lization.

The method of our invention is applicable to the treatment of virtually any beryllium ore in= cluding beryl, which is a beryllium aluminum silcate, and helvite, which is an iron aluminum beryllium silicate. Our method is applicable to any such ore or beryllium residue regardless of the other elements present and regardless of the beryllium content of the ore or residue. It will be noted from the following description and discussionof our novel method that it requires a quam tity of reagents suflicient to react only with the beryllium content of the beryllium ore or residue.

The beryllium ore or residue, which will be referred to collectively herein and in the claims as the ore, is preferably first reduced to a state of fine subdivision by grinding in a ball mill or the like. For example, the ore may be ground in a ball mill, either wet or dry, to a particle size of about 70% minus 200 mesh. The ore in this finely divided condition reacts readily at an elevated temperature with an alkali metal ferric fluoride or alkali metal fluosilicate. Although the method of our invention will be described and illustrated hereinafter by reference to the use of sodium ferric fluoride or sodium fluosilicate, it must be understood that the corresponding potassium salts may similarly be used with effective results.

The reaction between the beryllium component of the ore and sodium ferric fluoride, for example, takes place under normal roasting or sintering conditions as described in the aforementioned Kawecki patent. The mixture is advantageously shaped into briquettes, or the like, which may be heated for about one hour at a roasting temperature of about 750 C. Lower temperatures may be used but require longer roasting periods. There appears to be no advantage in raising the roasting temperature above about 750 C. although the reaction takes place satisfactorily at temperatures up to 900 C. and higher. The sodium ferric fluoride reacts with the beryllium of the ore to produce sodium beryllium fluoride (NazBeFr) generally according to the reaction The amount of sodium ferric fluoride required for this conversion is substantially only the stoichiometric quantity required for reaction with the beryllium oxide content of the ore. An excess of the fluoride is not required inasmuch as it does not enter into competing reactions with the aluminum, silicon and iron oxides of the ore. Actually, somewhat less than the stoichiome "ic amount of sodium ferric fluoride may be used with advantage. For example, when using about 90 of the stoichiometric quantity of the fluoride, a conversion of at least 95% of the beryllium content of the ore may be effected.

The conversion of the beryllium content of the ore into sodium beryllium fluoride may be effected, as noted hereinbefore, by roasting or sintering the ore with sodium fluosilicate (NazSiFe). The sodium fluosilicate appears to be equally as reactive as the sodium ferric fluoride and reacts under the same elevated temperature conditions as those described hereinbefore with respect to the use of sodium ferric fluoride.

The product of the roasting or sintering operation comprises sodium beryllium fluoride in admixture with oxides of iron, aluminum and silicon, together with somewhat smaller amounts of manganese and other oxides. The sodium beryllium fluoride is water-soluble and advan tage is taken of this characteristic in converting the sodium beryllium fluoride to ammonium beryllium fluoride.

The conversion of sodium beryllium fluoride to ammonium beryllium fluoride is facilitated by first reducing the sinter product to the finely divided condition by any suitable grinding procedure. The particle size of the ground sinter product is not critical. Merely for purposes of illustration, it may be noted that we have obtained excellent conversion with a sinter product reduced to a particle size of 50% minus 200 mesh.

The conversion of sodium beryllium fluorideto ammonium beryllium fluoride in accordance with our invention takes place readily in the presence of water. Although the water may be added either before or after the addition of the ammonium fluosilicate to the sinter product, we have found it particularly advantageous to add the water during the step of disintegrating the sinter product. The agitation provided by such a wetgrinding operation promotes dissolution of the sodium beryllium fluoride content of the sinter product. The amount of water added to the sinter product is not critical although we prefer to combine the advantage of adding water at this stage with the advantage of a wet-grinding procedure by using that amount of water which is conventionally added in wet-grinding prac tice. Thus, we have found it advantageous to effect wet-grinding of the sinter product in the presence of 1 to 5 parts by weight of added water,

and preferably about 2 parts by weight of added water. When using about 2 parts by weight of added water in the grinding operation, the ground product has a fluid, creamy, consistency.

The sodium beryllium fluoride in the sinter product is soluble in water at ambient room temperature to the extent of about 3 grams per liter expressed as BeO. Although the conversion of sodium beryllium fluoride to ammonium beryllium fluoride can be effected in accordance with our invention in the presence of sufiicient Water to hold all of the sodium beryllium fluoride in solution, we have found that it is not essential that all of the sodium beryllium fluoride be brought into solution before effecting this conversion by adding ammonium fluosilicate thereto. Thus, when using about 2 parts by weight of added water in the grinding operation, we have found this amount of water to be adequate for carrying out the conversion reaction even though the aqueous phase would have to contain about 20 grams of the sodium beryllium fluoride per liter, expressed as BeO, in order to hold all of the fluoride in solution. The discovery that this relatively small amount of water may be used makes it possible to keep the water content of the final product sufficiently low to permit economic recovery of the ammonium beryllium fluoride by conventional crystallization practice.

The. conversion of the sodium beryllium fluoride in the ground sinter product to ammonium beryllium fluoride is effected by adding thereto, in the presence of the added water, a slight stoichiometric excess of ammonium fluosilicate [(NHozSiFe]. The reaction between the ammonium fluosilicate and the sodium beryllium fluoride takes place immediately at ambient room temperature. Accordingly, there is no need to heat the-mixture of reactants, although the reaction will proceed satisfactorily at an elevated temperature. The reaction between the ammonium fluosilicate and sodium beryllium fluoride is substantially complete at normal temperatures and therefore requires only a slight stoichiometric excess of the ammonium fluosilicate to insure complete conversion. As the ammonium fluosilicate converts the dissolved sodium beryllium fluoride into the water-soluble ammonium beryllium. fluoride [(NH4)2BF4] and precipitates the water-insoluble sodium fluosilicate, additional sodium beryllium fluoride goes progressively into solution until all of the beryllium in the sinter product has been converted to ammonium beryllium fluoride.

The reaction between sodium beryllium fluoride and ammonium fluosilicate produces ammonium beryllium fluoride, which is watersoluble, and sodium fluosilicate, which is not appreciably water-soluble. The very slight watersolubility of sodium fluosilicate is still further depressed by the presence of the small stoichiometric excess of ammonium fluosilicate due to the well-known common ion effect. Thus, the product of the reaction between the water suspension of the disintegrated sinter product and the added ammonium fluosilicate comprises a red-colored residue comprising iron, aluminum and silicon oxides, together with the sodium fluosilicate precipitated in the course of the latter reaction, and a solution of the ammonium beryllium fluoride.

Separation of the ammonium beryllium fluoride solution from the accompanying residue may be eifected by any suitable filtering or decanting procedure. A rotary filter or filter press may be used with particular advantage for complete recovery of the ammonium beryllium fluoride. The filter cake is washed with a generous quantity of water to effect the desired recovery of entrained ammonium beryllium fluoride solution, although the amount of water used for this purpose is controlled so as not to dilute the filtrate unduly and thus complicate the subsequent crystallization operation.

Crystallization of ammonium beryllium fluoride from the filtrate may be effected directly without intermediate purification where the ammonium beryllium fluoride crystals are to be used in producing beryllium of commercial quality for use in copper or nickel base alloys, or the like. Crystallization may be efiected by any conventional evaporation procedure either of the batch or continuous type. In the case of continuous crystallization in particular, it is advantageous to carry out the evaporation only to the point where a small amount of mother liquor remains. The mother liquor, separated from the resulting crystals by centrifuging or the like, and containing a substantial amount of dissolved impurities, is then returned to the evaporating stage. The ammonium beryllium fluoride crystals may be used directly as removed from the centrifuge, that is, in their moist condition, or they may be dried prior to use. The crystals of ammonium beryllium fluoride thus obtained are ideally suited for use in the conventional reduction process in which metallic magnesium is employed to reduce the beryllium compound to beryllium metal.

The crystallization step is advantageously preceded by purification of the ammonium beryllium fluoride solution where the fluoride product is to be used in the production of pure metallic beryllium. The ammonium beryllium fluoride solution obtained as a filtrate upon separation of the red-colored residue containing precipitated sodium fluosilicate as well as the insoluble iron, aluminum and silicon oxides, generally contains small amounts of impurities in the form of soluble compounds of iron, manganese, copper and nickel. The filtrate does not contain any appreciable amount of aluminum as an impurity. Purification of the filtrate is advantageously effected in two stages. In the first stage, ammonium sulfide is added to the filtrate together with just enough ammonium hydroxide to raise the pH of the filtrate to the point where any more ammonium hydroxide would precipitate beryllium hydroxide. That is, ammonium hydroxide is added to the filtrateto bring its pH up to 5.5-6.0, and preferably to 6 about 538. The ammonium sulfide is added in amount suflicient to precipitate the dissolved iron, copper and nickel compounds as the sulfides. Dissolved manganese compounds are not precipitated in this stage of the purification. The precipitate comes down completely without heating and may be removed by filtering or decantation. However, heating the filtrate to which ammonium sulfide and ammonium hydroxide have been added helps to coagulate the precipitate and is recommended particularly Where separation of the precipitate is to be effected by decantation. The manganese remaining in solution is removed in the second stage of the purification procedure by adding ammonium persulfate to the filtrate in amount sufficient to precipitate the dissolved manganese compounds as manganese dioxide and by then heating the filtrate almost to boiling (i. e. to about 100 -C.). Manganese dioxide (M1102) is precipitated during the heating step and may be removed by filtering or decantation. The two purification stages may be carried out successfully in the reverse order if desired. The purified filtrate, freed from virtually all traces of such heavy metals as iron, manganese, copper and nickel, may then be subjected to evaporation for crystallization therefrom of pure crystals of ammonium beryllium fluoride.

It will be seen that the method of our present invention makes possible the recovery of beryllium from its ore in the form of ammonium beryllium fluoride without creating any health hazard. The roasting or s'intering operation may be conducted under a hood with complete assuranceoi the elimination of objectionable fumes. The subsequent treatment of the sinter product, including grinding in the presence of added water, reaction in the cold with ammonium fluosilicate, and simple evaporation of the resulting ammonium beryllium fluoride solution, is conducted in an aqueous condition and in the absence of any volatile substance of injurious nature. The process is also characterized by the use of relatively inexpensive reagents. The low cost of these reagents. together with the high recovery of -95% of the beryllium content of the ore, leads to production costs at least 25% below those associated with the most successful prior art methods.

We claim:

1. The method of producing ammonium beryllium fluoride from beryllium ore which comprises heating the ore with a double fluoride of an alkali metal and a'metal of the group consisting of iron and silicon to a temperature sufliciently high to eifect decomposition of the ore with the resulting production of sodium beryllium fluoride, disintegrating the sodium beryllium fluoride product in the presence of added Water, adding ammonium fluosilicate to the resulting product, and separating therefrom the aqueous phase comprising a solution of ammonium beryllium fluoride.

2. Themethod according to claim 1 in which the ammonium beryllium fluoride solution is treated with ammonium sulfide ata pH of 55- 6.0 to precipitate dissolved iron, copper and nickel impurities and is treated with ammonium persulfate to precipitate dissolved manganese impurities.

3. The method of producing ammonium beryllium fluoride from beryllium ore which comprises sintering the ore with a double fluoride of an alkali metal and a metal of the group consisting 7: of iron and silicon, disintegrating the sinter in the presence of added water, adding ammonium fluosilicate to the resulting aqueous mass, and separating therefrom the aqueous phase comprising a solution of ammonium beryllium fluoride.

4. The method of producing ammonium beryllium fluoride from beryllium ore which comprises sintering the ore with a double fluoride of an alkali metal and a metal of the group consisting of iron and silicon to produce sodium beryllium fluoride, disintegrating the sinter in the presence of added water, adding to the resulting aqueous mass an amount of ammonium fiuosilicate stoichiometrically in excess of that required to react with the sodium beryllium fluoride, and separating therefrom the aqueous phase comprising a solution of ammonium beryllium fluoride.

5. The method of producing ammonium beryllium fluoride from beryllium ore which comprises sintering the ore with a double fluoride of an alkali metal and a metal of the group consisting of iron and silicon, wet-grinding the sinter, adding ammonium fluosilicate to the resulting product, and separating therefrom the aqueous phase comprising a solution of ammonium beryllium fluoride.

6. The method of producing ammonium beryllium fluoride from beryllium ore which comprises sintering the ore with a double fluoride of an alkali metal and a metal of the group consisting of iron and silicon to produce sodium beryllium fluoride, wet-grinding the sinter, adding to the resulting product an amount of ammonium fiuosilicate stoichometrically in eX- cess of that required to react with the sodium beryllium fluoride, and separating therefrom the aqueous phase comprising a solution of ammonium beryllium fluoride.

7. The method of producing ammonium beryl lium fluoride from beryllium ore which comprises heating the ore with a double fluoride of an alkali metal and a metal of the group consisting of iron and silicon to a temperature sufliciently high to effect decomposition of the ore with the resulting production of sodium beryllium fluoride, disintegrating the sinter in the presence of 1 to parts by weight of added water, adding to the resulting aqueous mass an amount of ammonium fluosilicate stoichiometrically in excess of that required to react with the sodium beryllium fluoride, and separating therefrom the. aqueous phase comprising a solution of ammonium beryllium fluoride.

8. The method of producing ammonium beryllium fluoride from beryllium ore which comprises heating the ore with a double fluoride of an alkali metal and a metal of the group consisting of iron and silicon to a temperature sufficiently high to efiect decomposition of the ore with the resulting production of sodium beryllium fluoride, disintegrating the sinter in the presence of about 2 parts by weight of added Water, adding to the resulting aqueous mass an amount of ammonium fiuosilicate stoichometrically in excess of that required to react with the sodium beryllium fluoride, and separating therefrom the aqueous phase comprising a solution of ammonium beryllium fluoride.

9. The method of producing ammonium beryllium fluoride from beryllium ore which com- 7 prises heating the ore with a double fluoride of an alkali metal and a metal of the group consisting of iron and silicon to a temperature sufficiently high to effect decomposition of the ore ous phase comprising a solution of ammonium beryllium fluoride, and recovering the ammonium beryllium fluoride by crystallization from said solution thereof.

HENRY C. KAWECKI. GORDON F. SIMONS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,125,026 Jaeger July 26, 1938 2,145,329 Adamoli Jan. 31, 1939 2,173,290 Adamoli Sept. 19, 1939 2,312,2S7 Kawecki Feb. 23, 1943 2,381,291 Kjellgren Aug. 7, 1945 FOREIGN PATENTS Number Country Date 385,235 Great Britain Dec. 22, 1932 OTHER REFERENCES The Production of Beryllium Compounds, Metal and Alloys, by H. C. Kawecki. The Electrochemical Society. For release April 15, 1946. Preprint 89-11.

A Comprehensive Treatise on Inorganic and Theoretical Chemistry, by J. W. Mellor, vol. 4, 1923 ed., page 230, and vol. 6, 1925 ed., page 945. Longmans, Green and Company, New York, publishers. 

1. THE METHOD OF PRODUCING AMMONIUM BERYLLIUM FLUORIDE FROM BERYLIUM ORE WHICH COMPRISES HEATING THE ORE WITH A DOUBLE FLUORIDE OF AN ALKALI METAL AND A METAL OF THE GROUP CONSISTING OF IRON AND SILICON TO A TEMPERATURE SUFFICIENTLY HIGH TO EFFECT DECOMPOSITION OF THE ORE WITH THE RESULTING PRODUCTION OF SODIUM BERYLLIUM FLUORIDE, DISINTEGRATING THE SODIUM BERYLLIUM FLUORIDE PRODUCT IN THE PRESENCE OF ADDED WATER, ADDING AMMONIUM FLUOSILICATE TO THE RESULTING PRODUCT, AND SEPARATING THEREFROM THE AQUEOUS PHASE COMPRISING A SOLUTION OF AMMONIUM BERYLIUM FLUORIDE. 